Download Chloroplasts and Mitochondria

Mitochondria
Mitochondria are the powerhouses of the cell because they “burn” or break
the chemical bonds of glucose to release energy to do work in a cell.
Remember that this energy originally came from the sun and was stored in
chemical bonds by plants during photosynthesis. Glucose and other
carbohydrates made by plants during photosynthesis are broken down by
the process of aerobic cellular respiration (requires oxygen) in the
mitochondria of the cell. This releases energy (ATP) for the cell. The
more active a cell (such as a muscle cell), the more mitochondria it will
have. The mitochondria are bout the size of a bacterial cell and are often
peanut-shaped. Mitochondria have their own DNA and a double membrane
like the nucleus and chloroplast. The outer membrane is smooth, while the
inner membrane is convoluted into folds called cristae in order to
increase the surface area.
1. Why are mitochondria called the powerhouse of the cell?
2. What cell process occurs in the mitochondria?
3. Why do some cells have MORE mitochondria? Give an example.
4. What simple sugar is broken down in the mitochondria?
5. Where does the energy in glucose come from ORIGINALLY?
6. Where is this energy stored in glucose?
7. Why is cellular respiration an aerobic process?
1
8. What energy is released when the chemical bonds of glucose are
broken?
9. Name two other organelles besides the mitochondria that contain
DNA and have a double membrane.
10. Describe the outer membrane of the mitochondria.
11. Why is the inner mitochondrial membrane folded?
12. What are the folds called?
Color and label the outer membrane pink and the cristae red on figure
3. This greatly increases the surface area of the membrane so that
carbohydrates (simple sugars) can combine with oxygen to produce ATP,
adenosine triphosphate (the energy molecule of the cell). The electron
transport chain takes place across the membranes of the cristae
(crista, singular). Inside the folds or cristae is a space called the matrix
that contains enzymes needed for the Kreb's Cycle? Color and label
the matrix yellow on figure 3.
2
FIGURE 3 - MITOCHONDRIA
Mitochondria
Adenosine triphosphate (ATP) is the energy molecule used by all cells
to do work. It is a nucleotide consisting of a nitrogen-containing base
(adenine, thymine, cytosine, or guanine), a 5-carbon sugar, and 3 phosphate
groups. ATP is able to store and transport chemical energy within cells.
The LAST TWO phosphate groups (PO4), are joined by HIGH-ENERGY
bonds. When these bonds are broken, energy is released for cells to use
and ADP forms. Enzymes help to break and reform these high-energy
bonds.
13. What does ATP stand for?
14. What three main things make up an ATP molecule?
15. How many high-energy bonds does ATP contain?
16. Where are these high-energy bonds found in ATP?
17. What helps weaken these bonds so energy can be released and then
later help reform them?
18. When ATP loses a phosphate group __________ is released for cells
and a molecule of _________ forms.
3
In Figure 4, COLOR the 5-carbon sugar RED and LABEL it RIBOSE.
COLOR and LABEL the nitrogen-base DARK BLUE. COLOR and LABEL
the 3 phosphate groups YELLOW, and COLOR & LABEL the 2 highenergy bonds GREEN.
FIGURE 4 – ATP MOLECULE
4